Oil and gas hydrocarbons are naturally occurring in some subterranean formations. A subterranean formation containing oil or gas is sometimes referred to as a reservoir. A reservoir may be located under land or off shore. Reservoirs are typically located in the range of a few hundred feet (shallow reservoirs) to a few tens of thousands of feet (ultra-deep reservoirs).
In order to produce hydrocarbons, a wellbore is drilled through a hydrocarbon-bearing zone in a reservoir. In a cased-hole wellbore or portion thereof, a casing is placed, and typically cemented, into the wellbore providing a tubular wall between the zone and the interior of the cased wellbore. A tubing string can then be run in and out of the casing. Similarly, tubing string can be run in an uncased wellbore or section of wellbore. As used herein, “tubing string” refers to a series of connected pipe sections, joints, screens, blanks, cross-over tools, downhole tools and the like, inserted into a wellbore, whether used for drilling, work-over, production, injection, completion, or other processes. Further, in many cases a tool can be run on a wireline or coiled tubing instead of a tubing string, as those of skill in the art will recognize. A wellbore can be or include vertical, deviated, and horizontal portions, and can be straight, curved, or branched.
During completion of an open-hole wellbore portion, a completion tubing string is placed into the wellbore. The tubing string allows fluids to be introduced into, or flowed from, a remote portion of the wellbore. A tubing string is created by joining multiple sections of pipe together, typically via male right-handed threads at the bottom of an upper section of pipe and corresponding female threads at the top of a lower section of pipe. The two sections of pipe are connected to each other by applying a right-hand torque to the upper section of pipe while the lower section of pipe remains relatively stationary. The joined sections of pipe are then lowered into the wellbore. The process is referred to as “making up” and “running in” a string.
It is typical in hydrocarbon wells to actuate a downhole tool by relative longitudinal or rotational motion between tool parts caused by physical manipulation of the tool string, such as by placing weight down, lifting up, or rotating the string. Such actions are considered “mechanically operated” actuations, as opposed to electrically, hydraulically, or chemically operated. Mechanically operable tools can include release assemblies such as collet assemblies, expansion tools, packers, plugs, hangers, etc. Actuation can be used to “set” tools, release tools, open or close valves, etc. Other operations can be performed by the tool string as well. For example, a tubing string is run into a wellbore to hang an expandable liner and liner string, cement around the liner, expand the liner hanger, and release or disconnect the hung liner from the tool string. The string is then retrieved to the surface.
There is a need for tool assemblies, such as valves and release mechanisms, which can be mechanically operated. For example, a ball-drop actuated valve may not be operable or efficient in a horizontal bore at low tubing pressures.